Swimming in crude-slicked waters is an unsavory prospect at best and one that is most definitely unhealthful, although the molecular mechanics of why crude is so dangerous to humans are poorly understood, say toxics researchers.

Crude oil is a complex mixture of petrochemicals that includes all the most dangerous chemicals in gasoline, plus plenty of others -- clearly not something you want to be coated in.

"A lot of those chemicals are neurotoxins, which means they affect the brain," said Tracey Woodruff, an associate professor and director of the Program on Reproductive Health and the Environment at the University of California at San Francisco.

Dizziness, euphoria, nausea, blurry vision and headaches are a few of the short-term effects of such compounds as benzene, toluene, and xylenes, which are also found in gasoline. The symptoms can be a lot like a very bad case of alcohol poisoning, she said, which also foul up the workings of the nervous system.

There are long-term health dangers too. Benzene, in particular, has been tied to adult leukemia and other cancers. Benzene does this by entering cells and damaging DNA material, Woodruff said, although the specifics are not well understood.

What makes crude oil potentially even more dangerous, however, is that it contains so many toxic chemicals that can all attack the body at once, Woodruff explained.

"The combination can, in many cases, have more effect," Woodruff said. "It's like getting hit from different sides -- right hook, left hook and on top of the head."

This sort of multiple attack is less well understood, as most studies tend to focus on one chemical at a time.

Another variable is how differently the toxins can affect different sorts of people.

"It definitely would be worse for children to be exposed," said Woodruff. Infants and even unborn children could also be seriously harmed because the neurotoxins can interfere with brain development, she said.

Many of the toxins in crude oil can be absorbed directly through the skin or lungs, so the only way to avoid them is to keep away or wear protective gear like specially-designed respirators, boots, gloves and suits.

Workers already involved in the clean up are particularly at risk, of course, and they are already reporting symptoms of all sorts, including physical injuries from slipping on the oil, plus heat and fatigue, according to the National Institute for Occupational Safety and Health (NIOSH).

A NIOSH team of two industrial hygienists (specialists in workplace hazards) and two medical officers arrived in Louisiana on June 2 to evaluate illnesses and injuries among groups of offshore workers. The Louisiana Department of Health and Hospitals has also agreed to provide medical reports of seven previously hospitalized fishermen for the study.

"NIOSH is working with OSHA, Coast Guard, and others to collect and analyze data about the exposures that the Deepwater Horizon response workers may be encountering in various stages of activity (offshore and onshore), and symptoms that response workers are reporting," said Fred Blosser, a spokesman for NIOSH.

"We're working intensely, and data collection/analysis are in progress. This will give us a basis for assessing potential hazards in various operations, and making recommendations."

As for the handful of journalists who have decided to throw caution to the wind and swim in the muck unprotected, it's just unwise, Woodruff explained. "It seems like something even the birds are trying to avoid."